Maybe he legitimately didn't want to go to the Mariners, but as for the rest of them, this seems more likely:

These lists can usually be changed each off-season, and they generally are adjusted for leverage purposes. Agents stay on top of the rumor mill, and they figure out where the most likely destinations are for their client if he is going to be traded, then choose those organizations as the teams to block, giving them the most amount of leverage possible.

So, going back to the original question of the thread, the pattern is those teams all were perceived as a being fit for his services and as having the means to deal for him.

And maybe it's not all about leverage, maybe he legitimately doesn't want to several of those places, but I bet there are several places he'd less like to go that aren't on the list because they don't think it would ever come up.

At least you checked. I love all the people screaming "He's great in Arizona, sh*t everywhere else!!"

Considering Arizona is a launching pad, and he plays a huge chunk of his road games in SD, LA and SF, one should expect a huge split. I think he'd light it up in the AL East, playing all those games in TO, Baltimore and Fenway. The Yankees and O's should both be very interested.